There exists a plurality of rock-crushing apparatuses and methods for comminuting rocks into finer particles, such as gravel. Gravel is typically used for landscaping, and many other construction applications, etc. There are numerous uses for crushed stone. For instance, rock-crushing apparatuses are typically used to transform an uneven terrain into a practical road or path. More recently, the recreational industry has created a need for bicycle paths of gravel.
U.S. Pat. No. 3,701,485, issued on Oct. 31, 1972 to Kimble, discloses a “Rotor Construction for Impact Crusher.” U.S. Pat. No. 4,373,678, issued to Reitter on Feb. 15, 1983, is entitled “Rotary Impact Crusher Having a Continuous Rotary Circumference.” Both these patents describe impact crushers that include a rotary element that entrains rocks into a throat portion wherein rocks are crushed into finer particles. The crushing is caused by a combination of the action of the rotary element on the rocks caught in the throat portion, and impact between the rocks.
In designing rock-crushing apparatuses, a few factors are of importance. The performance of a rock crusher, i.e., the quantity of rock crushed with respect to time (e.g., tons/hour), is a primary feature in the rating of a rock-crushing apparatus. In the existing rock-crushing apparatuses, the rotary element is directly involved in the crushing of rocks by exerting a squeezing pressure on the rocks in the throat portion of the machine, whereby the rotary speed is directly related to the rate of production of the rock-crushing apparatuses.
It is also important that the rock-crushing apparatuses give consistent results. For instance, rock-crushing apparatuses are typically rated in accordance with the anticipated dimensions of the rock crushed by the apparatus. For instance, a rock-crushing apparatus can be rated as a zero- to two-inch crusher, in which case rock sizes go from minute particles to two inches at the exit of the apparatus. It is pointed out that the finer the range, the slower the speed of operation.
Another important factor is the durability of the rock-crushing apparatuses. Rock-crushing apparatuses undergo substantial wear of operating pieces. It is possible to increase the productivity of a rock-crushing apparatus if it is durable. Moreover, low maintenance and few repairs help in decreasing the costs related to operation of rock-crushing apparatuses.
These factors have a negative effect on each other. For instance, an increase in speed of the rotary element will most likely have an effect on the durability of the equipment. Moreover, the increased speed can damage the rotary element such that output of the rock-crushing apparatus becomes inconsistent. It would thus be desirable to have a rock-crushing apparatus that optimizes these factors.